"Since 2000, if I had taken £100 each time a fund manager moaned about August and exclaimed, 'I should have just stayed on the beach,' I could almost have afforded to stay on the beach, too," Clareville Capital's David Yarrow said.

Yarrow can joke: While his Pegasus Fund lost 4.9% last month, it is still up 4.1% on the year. Others are not so lucky.

Take Tudor Investment Corp.'s Tensor Fund: It lost 2.2% in August to extend its year-to-date decline to 6.2%, DealBreaker reports. And that loss is positively modest compared to some others.

Man Group's AHL Diversified strategy is off 7% on the year, Financial News reports. BlueCrest Capital Management's BlueTrend fund is down 11.6%, and International Standard Asset Management is down 12.9%.

Some funds managed to pick up ground in August, however. Elliott Management's International and Associates funds rose 0.9% on the month and are up 7.1% and 7.3% on the year, respectively, the New York Post reports. Varus Capital Management's eponymous fund is also up 7.3% in 2013 after a 2.11% jump in August.